Everyone knows if a train is running late, ONLY RailFans know WHY it is late

Saptagiri express was also a push-pull train , but not the same kind as the 22221/22 Raj.
After the train switched to electric traction, for a while it used to run with a WAM4 or a WAP1, with HOG (Head-on generation, like the Rajdhani trains today). Since the train ran on HOG, the loco could not be reversed at RU (disconnecting and reconnecting the HOG was not a simple task). So, to avoid this, SR used a special rake for Sapthagiri express.
The last SLR of the train had a duplicate...
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control stand, that mimicked the control stand of the locomotive. So, while going from MAS to RU, the loco used to lead the train. From RU to TPTY, the loco would be pushing the train from behind, while the LP controlled it using the control stand in the leading SLR. Thus, it was a 'Push-pull' train.
As it became difficult to maintain this mode of operations regularly, SR started attaching a second loco, instead of controlling it from the SLR.